Refining hydrocarbons



Patented Mar. 5, 1946 2,395,806 REFINING HYDROCARBONS du Bois Eastman, White Plains, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application May 1, 1943,

Serial No. 485,335

4 Claims.

This invention relates to the treatment of light hydrocarbons, such as naphtha and gasoline, to effect desulfurization. and to improve the anti-knock quality and susceptibility to antiknocking agents, 'such as tetraethyl lead, for the 5 purpose of improving the hydrocarbons for motor fuel.

In accordance with theinvention, the naphtha is contacted with adsorptive clay, such as fullers earth, under conditions which I choosev to term "depolymerizing conditions, In prior practice, naphtha stocks have been treated for desulfurization and improvement in lead susceptibility by contacting with clay catalysts, usually at temperatures within the range of about 650-750" F.

In the treatment of cracked naphtha. stocks which ordinarily contain quantities of readily 1 polymerizableolefins; difliculties have been encountered in'. this catalytic process, due to the fouling of the catalystby means of the ultimate products of polymerization which deposit'on the catalyst and shorten the catalyst life. I have discovered that if the temperature of the treat ment with the adsorptive clay be sufficiently high and the time of'reaction properly limited, de-

sulfurization, increase in anti-knock quality and improvement inlead response may be accomplished under essentially idepolymerizing conditions, such that there is no rapid fouling of the catalyst, with the result that the life of the cata- 0 lyst may be greatly increased. It would be expected that by going from relatively moderate temperatures, such as 650-750 F., tomaterially higher temperatures; the tendency for deposits on the catalyst would be greatly accentuated. Conis so retarded or prevented, and deposition of coke-or carbonaceous material on the catalyst is so reduced, that the life of the catalyst is greatly prolonged.

equilibrium is established under which any tendency towardpolymerization is ofiset by a'reversionback to the prepolymerized state, with the result that the operation may be conducted for extended periods of time without substantial deposition of the ultimate products of polymerization on the catalyst and without material im- 'pairment of the activity of the catalyst.

In practicing the invention, the naphtha stock is rapidly raised to a temperature of the. order of 900 F. and passed through a bed of adsorptive clay, such as fullers earth, with a time-of contact with the catalyst amounting to approximately 5-15 liquid volumes of feed per hour per volume of catalyst. Under these conditions reactions take place involving conversion'of sulfur compounds into hydrogen sulfide, isomerization of olefinic hydrocarbons and conversions or rearrangements of molecules functioning to increase anti-knock quality and lead response. The process is preferably conducted at relativelylow pressures, such as approximately atmospheric pressure or moderate superatmospheric pressures.

In an example of the invention, a naphtha stock consisting of approximately 80' per cent cracked naphtha and 20per cent high sulfur,

straight-run naphtha was rapidly passed through a heating coil thence intoa contacting chamber wherein it was passed through a bed of Riverside fullers earth atxa temperature of 950 F with a space velocityof 10. The following table gives the clear octane number of the charge" naphtha, the octane'number of the charge naphtha with 3 cc. of tetraethyl lead added, theweight percent of the sulfur content, and the distillation test. and also the clear'and leaded octane values,jthe sulfur contents (determined after washing with a caustic soda solution to remove hydrogen sulfide), the weight per cent of the sulfur reductions, and the distillation tests, on various samples of the treated product, taken during various periods of the run:

I Product Charge 0-6 4654 62+7 158-166 211-235 259-283 307-331 hrs. hrs hrs. hrs. hrs. hrs. hrs.

Octane0. F. R. M 64. 1 70. 4 65. 9 66.3 68. 1 66. 5 66. 9 67. 2 Octane-C F R. M. w1th3 cc TEL 73.8 78.9 77.5 76.2 I 77.0 77. 77.5 76.4 Sulfur-weight percent 0.125 0.077 0.055 0.065 0.075 0.073 0.094 0.104 Sulfur reduction-weight percent-. 39 56 48 40 25 l7 Distillation:

Initial 107 118 113 108 117 128 116 104 ''7 278 272 276 276 272 278 276 285 392 406 399 396 398 399 386 383 420 442 424 421 424 421 412 400 A characteristic feature of the invention is,

that under the high temperature conditions. thereis aperiod of pronounced activity for a relatively, short time at'thebeginning-of the run producing a considerable increase in the octane number and giving some evidence of polymerization, at least polymerization into products of intermediate boiling range. This runexemplifies such results. In the first six-hour period of the run representing a yield of 382barrels per ton of 7 catalyst, the clear octane number was raised 6.3 points; the distillation test furnishes evidence of some polymerization. After this rather brief octane number and lead response to be progressively reduced as the run proceeds. In this example of the invention, the run was terminated at the end of 331 hours, representing a yield .of 21,000 barrels per ton of clay. The sample taken at the end of the run for the last period had a satisfactory leaded octane number, although the sulfur reduction was low.

In practicing the inventionit is desirable to heat the ga'soline stock to the desired temperay ture of reaction as rapidly as possible so as to minimize oif avoid any strictly thermal converend boiling point of the 'gasoline being treated drogen sulfide and to thereby establish and maintain equilibrium conditions for an extended period of time under which the boiling distribution "range of the gasoline remains substantially unaltered and the tendency toward polymerization is offsetby reversion to the prepolymerized state to thus prevent substantial raising of the and to avoid material deposition on the catalyst of the ultimate products of polymerization so that a desulfurized gasoline product of improved motor fuel characteristics is produced.

s 3. The method of treating cracked gasoline stock for the removal of sulfur and improvement in characteristics as motor fuel which comprises continuously passing the gasoline vapors in 20 contact with fullers earth for an extended period of time, maintaining the vapors at a temperature of the order of 950 F. in contact with the clay catalyst and maintaining a time of contact of the vapors with the catalyst amounting to approximately 10 liquidvolumes per hour per volume of catalyst to thereby subjectthe'gasoline vapors to conditions adequate to produce effective conversion of sulfur compounds into hydrogen sulfide and to thereby establish and mainsion which might take place prio to contacting tain equilibrium conditions for an extended pewith the adsorptive clay.

Although a preferred embodiment of the ini pnhas' been described herein, it w n he derstood that various changes and modifications may be made therein, while securing to a greater or less extent some or all of the benefits of the invention, without departing from the spirit and fsoope thereof.

: 1; The method of treating gasoline stocks for 40 the removal of sulfur and improvement in characteristics as motor fuel which comprises con- A tinuously passing the gasoline vapors in contact with an adsorptive clay catalyst for'an extended period of time, maintaining the vapors at a temperature of about 900-950 F; in contact with the clay catalyst and maintaining a time of contact,

of the vapors with the catalyst amounting to ap-" proximately 5-15- liquid volumes per hour per volume of catalyst to thereby subject the gasoline vapors to conditions adequate to produce effective conversion .of sulfur compounds-into hydrogen sulfide and to therebyestablish and maintain equilibrium conditions for an extended period of time under which the boiling; distribution range of the gasoline remains substantially unaltered and the tendency toward polymerization is offset by reversion to the prepolymerlzed state to thus prevent substantial raising of the end boiling point of the gasoline bein treated and to avoid material deposition on the catalyst of the ultimate products of polymerization so that a desulfurized gasoline product of improved motor fuelcharacteristics is produced.

2. The method of treating cracked gasoline stocks for the removal of sulfur and improvement in characteristics as motor fuel which comprises continuously passing the gasoline vapors in contact with an adsorptive clay catalyst for an extended period of time, heating the vapors to a temperature of about 900-950 F. forcontact with the clay catalyst and maintaining a time of contact of the vapors with the catalyst amounting to approximately 5-15 liquid volumes per hour riodthrough a bedof adsorptive clay at a temriod of time under which the boiling distribution range of the gasoline remains substantially unaltered and the tendency toward polymerization is offset by reversion to the prepolymerized state 35 to thus prevent substantial raising of the end boiling point of the gasoline being treated and to avoid materialdeposition on the catalyst of the 1 ultimate productsof polymerization so that a desulfurized gasoline product of improved motor fuel characteristics is produced. 4, The method of treating gasoline stocks for the removal ofsulfurjand improvement in characteristics as motor fuel which'comprises initially passin asoline vapors for a relatively short peperatu're of about 900-950 F. and at a flow rate amounting to approximately 5-15 liquid volumes per hour per volume of catalyst to thereby effect reactions involving conversion of sulfur com- 0 poundsto hydrogen sulfide accompanied with some polymerization toformliquid polymers, continuing the passage of said vapors through the clay bed during said initial period until the formation of polymers is reduced and then continuing the passing of said vapors through the clay bed for an extendedperiod of time under said conditions of temperature and flow rate to thereby continue the subjection of the gasoline vapors to conditions adequate to produce effective conversion of sulfur compounds into hydrogensulfide and to thereby establish and maintain Y equilibrium conditionsfor an extended period of time underiwhich the boiling distribution range of the gasoline remains substantially unaltered and the tendency toward polymerization is offset by reversion to the prepolymerized state to thus I prevent substantialraising of the end boiling point of the gasoline and to avoid material deposition on the catalyst of the ultimate products 0 of polymerization so that'a desulfurized gasoline product of improved motor fuel characteristics is produced. 

